Information Flow Analysis and Consistency of Multilevel OS and DBMS Model

The security of database system (DBMS) is closely related to security of operation system (OS). Multilevel security DBMS can implement its security functions, such as mandatory access control (MAC), using the mechanisms of multilevel security OS only when the security policy of DBMS not violate the security policy of OS. Information flow analysis is beneficial to understanding the meaning and content of the security policies. The theory of information flow analysis is introduced at first. Before discussing the information flows, the multilevel security OS model and multilevel security DBMS model are presented. Then the information flows allowed in multilevel security OS and multilevel security DBMS are analyzed for the first time. The methods of analysis in OS and DBMS are similar: After concluding the objects that contain information, all the information flows among those objects are discussed according to the operations in the OS and DBMS. Because any object of DBMS can be mapped to one or a group of objects in OS, the category set of DBMS is a subset of the category set of OS. Finally the set of DBMS’s information flows is proved consistent with the one of OS’s information flows based on the definition of the consistence between two information flow sets. The conclusion guarantees the soundness of implementing mandatory access control of multilevel security DBMS using the mechanisms of multilevel security OS.